/*
 * XXX ab@apache.org: This class is copied verbatim from Xalan-J 2.6.0
 * XXX distribution, org.apache.xml.utils.XMLCharacterRecognizer,
 * XXX in order to avoid dependency on Xalan.
 */

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/*
 * $Id: XMLCharacterRecognizer.java,v 1.7 2004/02/17 04:21:14 minchau Exp $
 */
package org.apache.nutch.parse.html;

/**
 * Class used to verify whether the specified <var>ch</var> conforms to the XML
 * 1.0 definition of whitespace.
 */
public class XMLCharacterRecognizer {

	/**
	 * Returns whether the specified <var>ch</var> conforms to the XML 1.0
	 * definition of whitespace. Refer to
	 * <A href="http://www.w3.org/TR/1998/REC-xml-19980210#NT-S"> the definition
	 * of <CODE>S</CODE></A> for details.
	 * 
	 * @param ch
	 *            Character to check as XML whitespace.
	 * @return =true if <var>ch</var> is XML whitespace; otherwise =false.
	 */
	public static boolean isWhiteSpace(char ch) {
		return (ch == 0x20) || (ch == 0x09) || (ch == 0xD) || (ch == 0xA);
	}

	/**
	 * Tell if the string is whitespace.
	 * 
	 * @param ch
	 *            Character array to check as XML whitespace.
	 * @param start
	 *            Start index of characters in the array
	 * @param length
	 *            Number of characters in the array
	 * @return True if the characters in the array are XML whitespace;
	 *         otherwise, false.
	 */
	public static boolean isWhiteSpace(char ch[], int start, int length) {

		int end = start + length;

		for (int s = start; s < end; s++) {
			if (!isWhiteSpace(ch[s]))
				return false;
		}

		return true;
	}

	/**
	 * Tell if the string is whitespace.
	 * 
	 * @param buf
	 *            StringBuffer to check as XML whitespace.
	 * @return True if characters in buffer are XML whitespace, false otherwise
	 */
	public static boolean isWhiteSpace(StringBuffer buf) {

		int n = buf.length();

		for (int i = 0; i < n; i++) {
			if (!isWhiteSpace(buf.charAt(i)))
				return false;
		}

		return true;
	}

	/**
	 * Tell if the string is whitespace.
	 * 
	 * @param s
	 *            String to check as XML whitespace.
	 * @return True if characters in buffer are XML whitespace, false otherwise
	 */
	public static boolean isWhiteSpace(String s) {

		if (null != s) {
			int n = s.length();

			for (int i = 0; i < n; i++) {
				if (!isWhiteSpace(s.charAt(i)))
					return false;
			}
		}

		return true;
	}

}
